Throughout this application various publications are referenced within parentheses. The disclosures of these publications in their entireties are hereby incorporated by reference in this application in order to more fully describe the state of the art to which this invention pertains.
1. The Field of the Invention
This invention relates to the medical arts. In particular the present invention relates to the field of cellular signal transduction and to gene therapy.
2. Discussion of the Related Art
Cytokines are small secreted proteins or factors (5 to 20 kD) that have specific effects on cell-to-cell interactions, intercellular communication, or the behavior of other cells. Cytokines involved in inflammatory diseases are produced by lymphocytes, especially TH1 and TH2 lymphocytes, monocytes, intestinal macrophages, granulocytes, epithelial cells, and fibroblasts. (Reviewed in G. Rogler and T. Andus, Cytokines in inflammatory bowel disease, World J. Surg. 22(4) 382-89 [1998]; H. F. Galley and N. R. Webster, The immuno-inflammatory cascade, Br. J. Anaesth. 77:11-16 [1996]). Some cytokines are pro-inflammatory (e.g., tumor necrosis factor [TNF]-α, interleukin [IL]-1(α and β), IL-6, IL-8, IL-12); others are anti-inflammatory (e g., IL-1 receptor antagonist [IL-1ra], IL-4, IL-10, IL-11, and transforming growth factor [TGF]-β). However, there may be overlap and functional redundancy in their effects under certain inflammatory conditions.
One group of cytokines, the IL-6-type, are also important in the regulation of complex cellular processes such as gene activation, proliferation and differentiation The IL-6-type cytokines include IL-6, IL-11, leukemia inhibitory factor (LIF), oncostatin M, ciliary neutrophic factor, and cardiotrophin-1. (Reviewed in P. C. Heinrich et al., Interleukin-6-type cytokine signaling through the gp130/JAK/STAT pathway, Biochem. J. 334(Pt 2):297-314 [1998]). The IL-6-type cytokines (also known as the gp130 signaling subunit cytokine family) have in common that signal transduction proceeds through a pathway beginning with ligand binding by type I and type II surface receptors, internalization involving affinity converter/signal transducing subunit gp 130, the activation of the Janus family of cytoplasmic tyrosine kinases (e.g., Jak1, Jak2, and Tyk2); this results in the phosphorylation and dimerization of the signal transducers and activators of transcription (STAT)-1 and STAT-3that activate transcription from promoters having STAT recognition sites. (Heinrich et al. [1998]; M. Ernst et al., Gp130-mediated signal transduction in embryonic stem cells involves activation of Jak and Ras/mitogen-activated protein kinase pathways, J. Biol. Chem. 271(47):30136-43 [1996]; R. Starr et al., A family of cytokine-inducible inhibitors of signaling, Nature 387(6636):917-21 [1997]; T. Hirano et al., Cytokine & Growth Factor Rev. 8:241-52 [1997]; E. Arzt & G. K. Stalla, Neuroimmunomodulation 3:28-34 [1996]; S. J. Haque & B. R. G. Williams, Semin. Oncol. 25 (suppl. 1):14-22 [1998]). This pathway is known as the Jak-STAT signaling cascade.
Several IL-6-type cytokines are important neuro-immuno-endocrine modulators of the hypothalamo-pituitary-adrenal (HPA) axis (Arzt, E. & Stalla [1996]; S. Melmed, Trends Endocrinol. Metab. 8:391-97 [1997]; H. O. Besedovsky, & A. Del Rey, Endo. Rev. 17:64-102 [1996]), which regulates metabolism, including growth, body temperature, water balance, blood sugar, fat metabolism, and sexual and nerve function. For example, LIF is a potent auto-paracrine stimulus of pituitary proopiomelanocortin (POMC) gene expression and adrenocorticotrophic hormone (ACTH) secretion, which stimulates the adrenals to produce additional hormones. Thus, LIF modulates the HPA axis response to various inflammatory and stress stimuli. (Z. Wang et al., Endocrinology 137:2947-53 [1996]; C. J. Auernhammer et al., Endocrinology 139:2201-08 [1998a]). In vitro experiments using human fetal pituitary cells (I. Shimon et al., J. Clin. Invest. 100: 357-63 [1997]) and the corticotroph cell line AtT-20 (S. Akita et al., J. Clin., Invest 95, 1288-1298 [1995]; C. Bousquet et al., J. Biol. Chem 272:10551-57 [1997]), showed a profound and synergistic action of LIF and corticotropin-releasing hormone (CRH) on POMC gene expression and ACTH secretion LIF is known to induce the Jak-STAT signaling cascade in the corticotroph cells. (C. J. Auernhammer et al., Pituitary corticotroph SOCS-3: novel intracellular regulation of leukemia-inhibitory factor-mediated proopiomelanocortin gene expression and adrenocorticotropin secretion, Mol. Endocrinol. 12(7):954-61 [1998b]; I. Shimon et al. [1997]; D. W. Ray et al., Leukemia inhibitory factor (LIF) stimulates proopiomelanocortin (POMC) expression in a corticotroph cell line. Role of STAT pathway, J. Clin. Invest. 97(8):1852-59 [1996]; D. W. Ray et al., Ann. N. Y. Acad. Sci. USA 840:162-73 [1998]).
A new family of cytokine-inducible proteins has recently been described that inhibits the Jak-STAT signaling cascade (E.g., S. E. Nicholson et al., The SOCS proteins: a new family of negative regulators of signal transduction, J. Leukoc. Biol. 63(6):665-68 [1998]; R. Starr et al., SOCS: suppressors of cytokine signaling, Int. J. Biochem. Cell. Biol. 30(10):1081-85 [1998]). These proteins have been variously termed suppressors of cytokine signaling (“SOCS”)(R. Starr et al., A family of cytokine-inducible inhibitors of signaling, Nature 387(6636):917-21 [1998], D. J. Hilton et al., Proc. Natl. Acad. Sci. USA 95:114-19 [1998]), STAT-induced STAT inhibitors (SSI)(T. Naka et al., Nature 387:924-28 [1997]; S. Minamoto et al., Biochem. Biophys. Res. Commun 237:79-83 [1997]), cytokine-inducible SH2 containing protein (CIS)(A. Yoshimura et al., EMBO J. 14:2816-26 [1995]; M. Masuhara et al., Biochem. Biophys. Res,. Commun. 239:439-46 [1997]; A, Matsumoto et al., Blood 89:3148-54 [1997]), and Jak binding protein (JAB)(T. A. Endo et al., Nature 387:921-24 [1997]; H. Sakamoto et al., Blood 92 1668-76 [1998]). The SOCS-protein family currently consists of CIS and SOCS-1 through 7 (D. J. Hilton et al.[1998]; M. J. Aman & W. J. Leonard, Curr. Biol. 7:R784-R788 [1997]; R. Starr & D. J. Hilton, Int. J. Biochem. Cell Biol. 30:1081-85 [1998]).
SOCS-protein expression is stimulated by various cytokines in a tissue specific manner (R. Starr et al., Nature 38: 917-21 [1997]; M. J. Aman & W. J. Leonard [1997]; H. Sakamoto et al. [1998]; H. O. Besedovsky, & A. Del Rey [1996]; T. E. Adams et al., J. Biol. Chem. 273:1285-87 [1998]; C. Bjorbaek et al., Mol. Cell 1:619-625 [1998]). The gene expression of SOCS-1/SSI-1/JAB and SOCS-3/SSI-3/CIS-3, referred to herein as SOCS-1 and SOCS-3, are induced by IL-6 and LIF in various tissues (R. Starr et al. [1997]; D. J. Hilton et al. [1998]; T. Naka et al. [1997]; S. Minamoto et al. [1997]; M. Masuhara et al. [1997]; A. Matsumoto et al. [1997]; T. A. Endo et al. [1997]). For example, SOCS-3 gene expression is rapidly induced by LIF in the pituitary in vivo, and in corticotroph AtT-20 cells in vitro. (C. J. Auernhammer et al. [1998b]).
Both, SOCS-1 and SOCS-3 proteins bind to the JH1 domain of Jak-2 and thereby inhibit IL-6-, IL-11-, or LIF-induced tyrosine phosphorylation activity by Jak-2 of gp 130 and STAT-3 (S. Minamoto et al. [1997]; M. Masuhara et al. [1997]; C. J. Auernhammer et al. [1998b]). SOCS-3 is induced by growth hormone (GH) in the liver, and inhibits GH-induced Spi 2.1 promoter activity. (T. E. Adams et al. [1998]). SOCS-3 inhibits LIF-induced POMC gene expression and ACTH secretion (C. J. Auernhammer et al. [1998b]), thus providing an intracellular negative feedback regulation of cytokine-induced activation of the HPA-axis. Hypothalamic SOCS-3 gene expression is stimulated by leptin, and SOCS-3inhibits leptin-induced signal transduction (C. Bjorbaek et al., Mol. Cell 1:619-625 [1998]), thus suggesting its regulatory role in central leptin resistance.
The structure of SOCS proteins has been described. (e.g., S. E. Nicholson et al., Mutational analyses of the SOCS proteins suggest a dual domain requirement but distinct mechanisms for inhibition of LIF and IL-6 signal transduction, EMBO J. 18(2):375-85 (January 1999). Dominant negative STAT-3 mutants, isolated by substitution of a carboxy-terminal tyrosine phosphorylation site Tyr705 to Phe705 (STAT-3F) or mutation at positions important for DNA binding (STAT-3D) have been recently described (K. Nakajima et al., EMBO J. 15:3651-58 [1996]). Overexpression of these STAT-3 dominant negative mutants in corticotroph AtT-20 cells inhibits LIF-induced POMC gene expression and ACTH secretion. (C. Bousquet & S. Melmed, J. Biol. Chem. 274:10723-30 [1999]). Cytokine-induced gene expression of SOCS-1 has been shown to be inhibited in cells overexpressing dominant negative STAT-3 mutants (T. Naka et al. [1997]), but the promoter region of SOCS-1 has not been cloned.
Therefore, there remains a definite need for a promoter sequence capable of regulating expression of preselected proteins, such as SOCS-3 protein, and that can be targeted by gene therapy to treat growth disorders, autoimmune diseases, immune diseases, and inflammatory conditions. This and other features and benefits provided by the present invention will now be described.